Question

1) Tyrion is pulling a 30 kg sled loaded with ale across an ice lake. Assume the sled starts from rest and that it moves a distance of 10 m to the right. He pulls the sled to the right with a force of 300 N at angle of 30° above the horizontal. Once again, Cersei is trying to stop Tyrion from leaving and pulls on the sled horizontally to the left with a force of 100 N. Find the kinetic energy and speed of the sled after the 10 m move. 2) Jon Snow gets onto the lift at the top of the wall and begins to descend down to Castle Black. Part of the way down, the cables holding the lift begin to slip. The combined mass of Snow and the lift is 250 kg. The lift now accelerates downward with an acceleration of 2g/5, where g is the acceleration of gravity. If the lift travels 300 meters before crashing, answer the following questions. a) How much work is done by the tension in the lift cables? b) How much work is done by the force of gravity? c) If the lift was going 1m/s downward when the cable began to slip, at what velocity does the lift crash into the ground?

Answer 1

1] Work done by all forces = Change in KE

Work done by Tyrion + work done by Cersei = 0.5mv^2

300*10* cos 30 degree - 100*10 = 0.5*30*v^2

v = 10.32 m/s answer